US20180183213A1 - Semiconductor laser - Google Patents

Semiconductor laser Download PDF

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US20180183213A1
US20180183213A1 US15/737,139 US201615737139A US2018183213A1 US 20180183213 A1 US20180183213 A1 US 20180183213A1 US 201615737139 A US201615737139 A US 201615737139A US 2018183213 A1 US2018183213 A1 US 2018183213A1
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area
layer
semiconductor laser
semiconductor
substrate
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Tsukuru Katsuyama
Takashi Kato
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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Priority claimed from JP2015180925A external-priority patent/JP6613747B2/ja
Priority claimed from JP2016156514A external-priority patent/JP2018026429A/ja
Application filed by Sumitomo Electric Industries Ltd filed Critical Sumitomo Electric Industries Ltd
Assigned to SUMITOMO ELECTRIC INDUSTRIES, LTD. reassignment SUMITOMO ELECTRIC INDUSTRIES, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KATO, TAKASHI, KATSUYAMA, TSUKURU
Publication of US20180183213A1 publication Critical patent/US20180183213A1/en
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    • H—ELECTRICITY
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    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/3401—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers having no PN junction, e.g. unipolar lasers, intersubband lasers, quantum cascade lasers
    • H01S5/3402—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers having no PN junction, e.g. unipolar lasers, intersubband lasers, quantum cascade lasers intersubband lasers, e.g. transitions within the conduction or valence bands
    • H—ELECTRICITY
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    • H01S5/00—Semiconductor lasers
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H—ELECTRICITY
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    • H01S5/00—Semiconductor lasers
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H01S5/0425—Electrodes, e.g. characterised by the structure
    • H—ELECTRICITY
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    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
    • H01S5/06203—Transistor-type lasers
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    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure
    • H01S5/227—Buried mesa structure ; Striped active layer
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    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/3401—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers having no PN junction, e.g. unipolar lasers, intersubband lasers, quantum cascade lasers
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    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/3408—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers characterised by specially shaped wells, e.g. triangular
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    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/343—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/34313—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser with a well layer having only As as V-compound, e.g. AlGaAs, InGaAs
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    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/343—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/34346—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser characterised by the materials of the barrier layers
    • H—ELECTRICITY
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    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H01S5/0421—Electrical excitation ; Circuits therefor characterised by the semiconducting contacting layers
    • H01S5/0422—Electrical excitation ; Circuits therefor characterised by the semiconducting contacting layers with n- and p-contacts on the same side of the active layer
    • H01S5/0424—Electrical excitation ; Circuits therefor characterised by the semiconducting contacting layers with n- and p-contacts on the same side of the active layer lateral current injection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H01S5/0425—Electrodes, e.g. characterised by the structure
    • H01S5/04256—Electrodes, e.g. characterised by the structure characterised by the configuration
    • H—ELECTRICITY
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    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H01S5/0425—Electrodes, e.g. characterised by the structure
    • H01S5/04256—Electrodes, e.g. characterised by the structure characterised by the configuration
    • H01S5/04257—Electrodes, e.g. characterised by the structure characterised by the configuration having positive and negative electrodes on the same side of the substrate

Definitions

  • the present invention relates to a semiconductor laser that has a radiation mechanism using unipolar carriers.
  • a Japanese Patent Document laid open No H08-279647A has disclosed a quantum cascade laser using radiative transitions between energy levels by unipolar carries in active layers arranged in series, which is sometimes called as the cascaded radiative transition.
  • energy levels in one active layer are necessary to be aligned with energy levels in active layers next to the one active layer. Specifically, a higher energy level in the one active layer is aligned with a lower energy level in the upstream active layer, and a lower energy level in the one active layer is aligned with a higher energy level in the downstream active layer.
  • Such a cascaded radiative transition may enhance the optical gain in infrared wavelengths, and resultantly, the cascaded radiative transition realizes the laser oscillation in infrared regions.
  • the cascaded radiative transition is inevitable to be supplied with a large bias, which resultantly prohibits a cascade layer from operating in reduced biases.
  • An aspect of the present invention relates to a semiconductor laser that comprise a substrate, an active area, an emitter area, and a collector area, where the active area, the emitter area and the collector area are laterally arranged on a top surface of the substrate such that the emitter area and the collector area sandwich the active area therebetween.
  • the active area provides a quantum well structure.
  • the emitter area has a first conduction type
  • the collector area also has the first conduction type same with that of the emitter area.
  • the quantum well structure in the active area causes a radiative transition from a higher energy level to a lower energy level of carriers with the first conduction type. The higher energy level is lower than or equal to an energy level of the carriers in the emitter area, and the lower energy level is higher than or equal to an energy level of the carriers in the collector area.
  • FIG. 1 schematically illustrates a fundamental arrangement of a semiconductor laser and modified arrangements of a semiconductor laser of the present invention.
  • FIG. 2 schematically illustrates an arrangement of energy levels induced in the quantum well structure in the active area of the semiconductor laser.
  • FIG. 3 illustrates an energy level diagram in the quantum well structure.
  • FIG. 4 illustrates another energy level diagram in the quantum well structure.
  • FIG. 5 schematically illustrates another fundamental arrangement of a semiconductor laser modified from those shown in FIG. 1 .
  • FIG. 6 illustrates still another arrangement of the semiconductor laser shown in FIG. 5 .
  • FIGS. 7( a ) to 7( d ) schematically illustrate process of forming the semiconductor laser of the present invention shown in FIG. 5 .
  • FIGS. 8( a ) to 8( d ) schematically illustrate the processes subsequent to that shown in FIG. 7( d ) .
  • FIGS. 9( a ) to 9( d ) schematically illustrate the processes of forming the semiconductor laser shown in FIG. 6 .
  • the semiconductor laser comprises (a) a substrate having a top surface that includes first to third areas, (b) an active area provided on the first area of the substrate, where the active area includes a quantum well structure having a plurality of semiconductor layers stacked along a first axis intersecting the top surface, (c) an emitter area provided on the second area of the substrate, where the emitter area has a first semiconductor material with a first conduction type and is in contact to the active area, and (d) a collector area provided on the third area of the substrate, where the collector area has a second semiconductor material with the first conduction type and is in contact to the active area.
  • a feature of the semiconductor laser of the present embodiment is that the first and second areas are arranged along a second axis that intersects the first axis, the first and third areas are arranged along a third axis that intersects the first axis, and the second area is apart from the third area.
  • the semiconductor laser of the present invention injects carriers with the first conduction type from the emitter area into the active area and carries supplied into the active area flows into the collector area after making radiative transitions in the active area.
  • the carries incoming the active area from the emitter area contribute to the emission by the radiative transition from an upper energy level to a lower energy level formed in the quantum well structure.
  • the active area on the first area and the emitter area on the second area are arranged along the second axis intersecting the first axis, while, the active area on the first area and the collector area on the third area are arranged along the third axis intersecting the first axis.
  • the emitter area in the second area laterally couples with the collector area in the third area through the active area in the first area.
  • the emission from the semiconductor laser of the present invention is only due to the radiative transition within the quantum well structure, and is unnecessary for cascading emissions of the unipolar carriers as those occurring in a cascade laser.
  • the semiconductor laser of the invention in the quantum well structure thereof provides a first well layer, a second well layer, a first barrier layer, and a second barrier layer, where the first barrier layer demarcates the first well layer from the second well layer, while, the first and second well layers demarcate the first barrier layer from the second barrier layers, respectively.
  • the quantum well structure thus configured provides a higher energy level and a lower energy level for the unipolar carriers.
  • the quantum well structure may further provide a relaxation level lower than the lower energy level. The relaxation level may show a relaxation time for the carriers fallen from the lower energy level which is shorter than a relaxation time for the carrier fallen from the higher energy level to the lower energy level.
  • the semiconductor laser of the invention may include unit cells sequentially stacked on the substrate, where each of the unit cells includes the first and second well layers, and the first and second barrier layers.
  • a feature of the quantum well structures of the semiconductor laser is that the first barrier layer arranged between the first and second well layers, which may be called as the inner barrier layer, has a thickness less than that of the second barrier layers that sandwich the first and second well layers and the first barrier layer, where the second barrier layers may be called as the outer barrier layers.
  • the quantum well structure thus configured may couple the first well layer with the second well layer tightly because of the thinned inner barrier layer.
  • the barrier layer may be doped with impurities showing the conduction type same with the conduction type of the carriers.
  • FIG. 1 schematically illustrates a cross section of a semiconductor laser of one embodiment of the present invention.
  • the semiconductor laser 11 provides a substrate 13 , an active area 15 , an emitter area 17 , and a collector area 19 .
  • the substrate 13 provides a top surface 13 a that includes a first area 13 b , a second area 13 c , and a third area 13 d .
  • the active area 15 which is provided on the first area 13 b , includes a quantum well structure 21 that has a plurality of well layers and a plurality of barrier layers, 21 a to 21 d .
  • These semiconductor layers, 21 a to 21 d are arranged along a first axis Ax 1 , which is the Y-axis of the Cartesian coordinate; that is, these semiconductor layers, 21 a to 21 d , are stacked on the top surface 13 a of the substrate 13 .
  • the emitter area 17 provides a first semiconductor material 23 with a first conduction type, where the first semiconductor material 23 is arranged on the second area 13 c ; while, the collector area 19 provides a second semiconductor material 25 with the first conduction type, where the second semiconductor material 25 is arranged on the third area 13 d .
  • the first and third areas, 13 b and 13 d are arranged along a direction intersecting the first axis Ax 1 , namely, the positive direction of the X-axis of the Cartesian coordinate.
  • the first and second areas, 13 b and 13 c are arranged along the direction, namely, the negative direction of the X-axis of the Cartesian coordinate. Referring to the cross section shown in FIG.
  • the first area 13 b is put between the second area 13 c and the third area 13 d ; that is, the second area 13 c is spatially apart from the third area 13 d by the first area 13 a .
  • the emitter area 17 is electrically divided from the collector area 19 . Carriers supplied to the emitter area 17 flow within the collector area 19 though the active area 15 .
  • the emitter area 17 is in contact to a side 15 b of the active area 15 to supply the carriers with the first conduction type, namely, one of the electrons and the holes.
  • the collector area 19 is also in contact to another side 15 c of the active area 15 to receive the carriers with the first conduction type.
  • the semiconductor laser 11 of the embodiment provides the active area 15 on the first area 13 b and the emitter area 17 on the second area 13 c each arranged along a direction intersecting the first axis Ax, and the active area 15 on the first area 13 b and the collector area 19 on the third area 13 d each arranged along a direction also intersecting the first axis Ax.
  • Carriers are supplied from the emitter area 17 to the active area 15 as hot carriers CAE and contribute to the emission in the active area 15 by the radiative transition from the upper energy level of the quantum well structure 21 to the lower energy level of the quantum well structure 21 .
  • the carriers after the transition in the active area 15 flow into the collector area 19 as cold carriers CAC.
  • the semiconductor laser 11 of the embodiment utilizes the radiative transition of the carriers with the same conduction type, that is, the semiconductor laser 11 does not utilize the radiative recombination between the electrons and the holes accompanying with the emission. Moreover, the arrangement of the emitter area 17 , the active area 15 , and the collector area 19 , namely, laterally arranged on the substrate 13 , makes the cascading transition of the carriers unnecessary. Thus, the semiconductor laser 11 may reduce a bias to operate the semiconductor laser 11 .
  • FIG. 2 schematically illustrates the quantum well structure and the energy levels of the semiconductor laser 11 of the present embodiment.
  • the vertical axis corresponds to the energy level E; while, the horizontal axes correspond to the X- and Y-axes shown in FIG. 1 .
  • the explanation in FIG. 2 concentrates on the carrier of the type of the electron, but the explanation may be applicable to the carrier of the type of the hole based on the fundamental semiconductor physics.
  • the active area 15 of the embodiment includes one or more unit cells 15 a each comprising a first well layer 21 a , a second well layer 21 b , a first barrier layer 21 c , and a second barrier layer 21 d .
  • the second barrier layer 21 d which is the inner barrier layer, divides the first well layer 21 a from the second well layer 21 b ; while, the first well layer 21 a and the second well layer 21 b divide the first barrier layers 21 c , which are the outer barrier layers, from the inner barrier layer 21 d , respectively.
  • the unit cell 15 a thus arranged may cause discrete energy levels by a width and a depth of the well layers and a width of the inner barrier layer 21 d , where the depth of the well layers may be determined by a difference in the energy levels between the well layer and the barrier layer for the carriers under consideration.
  • the unit cell 15 a of the embodiment which is formed by two well layers, 21 a and 21 b , and two barrier layers, 21 c and 21 d , alternately stacked to each other, causes the upper energy level E 3 and the lower energy level E 2 each for the electrons, and also a relaxation energy level E 1 below the lower energy level E 2 .
  • the relaxation energy level E 3 when it is induced in the well layer, may accelerate non-radiative transition of the carrier from the lower energy level E 2 by a relaxation time shorter, preferably far shorter, than a relaxation time for the transition of the carriers from the higher energy level E 3 to the lower energy level E 2 .
  • the carriers namely, the electrons in the present embodiment are injected into the active area 15 from the emitter area 17 .
  • the injected electrons cause the radiative transition from the upper energy level E 3 to the lower energy level E 2 , which generates light.
  • the electrons falling into the lower level E 2 are immediately relaxed to the relaxation level E 1 and finally drawn into the collector area 19 therefrom.
  • This mechanism means that the lower energy level E 2 shows lesser occupancy of the carriers.
  • the energy diagram of the present embodiment may accelerate the generation of the population inversion of the carriers.
  • the unit cells 15 a which is arranged along the stacking direction Ax 1 , forms the active area 15 .
  • the emitter area 17 which is arranged aside of the active area 15 , provides the carries concurrently into the respective unit cells 15 a .
  • the unit cells 15 a responding the supplement of the carries at the upper energy level E 3 , causes the radiative transition from the upper energy level E 3 to the lower energy level E 2 , and generates light concurrently.
  • the carriers fallen in the lower energy level E 2 are immediately fallen into the relaxation level E 1 and flow out to the collector area 19 .
  • the emitter area In order to accelerate the injection of the carriers into the active area 15 , the emitter area has an energy level E 17 , typically the bottom energy level of the conduction band thereof, is substantially equal to or higher than the higher energy level E 3 in the well layers, 21 a and 21 b . Also, in order to enhance the exhaustion of the carriers from the active area 15 , the collector area 19 has an energy level E 19 , which is a bottom energy level of the conduction band thereof, is substantially equal to or lower than the relaxation energy level E 1 in the well layers, 21 a and 21 c.
  • the inner barrier layer 21 d partitions two well layers, 21 a and 21 b . Because the inner barrier layer 21 d has a thickness TB 1 thinner than a thickness TB 2 of the outer barrier layer 21 c , the coupling of the well layers, 21 a and 21 b , may easily occur; exactly, the wave functions attributed to the respective layers, 21 a and 21 b , oozing into the second barrier layer 21 d may effectively couple to each other in the inner barrier layer 21 d . Thus, the energy levels may be determined solely by the respective unit cells 15 a.
  • the mesa MS which includes the active area 15 that extends along the direction Z, physically divides the emitter area 17 from the collector area 19 .
  • the mesa MS may also include the first cladding layer 27 as the upper cladding layer on the active area 15 .
  • the upper cladding layer 27 preferably has resistivity greater than that of an average resistivity of the active area 15 , or the upper cladding layer 27 may be an insulating or semi-insulating layer.
  • the semiconductor laser 11 may also provide the second cladding layer 29 as the lower cladding layer beneath the active area 15 .
  • the lower cladding layer 29 preferably has resistivity greater than that in an average of the active area 15 , or the lower cladding later may be an insulating or semi-insulating layer.
  • the upper and lower cladding layers, 27 and 29 show not only the function of the optical confinement of the light within the active area 15 but the function of the electrical confinement of the carriers also within the active area 15 .
  • the upper and lower cladding layers, 27 and 29 may be, as described above, an insulating or semi-insulating layer; but the upper and lower cladding layers, 27 and 29 , may have the conduction type opposite to the conduction type of the carriers.
  • the substrate 13 which may be made of insulating or semi-insulating material, has the top surface 13 a .
  • the insulating or semi-insulating characteristic of the substrate 13 may effectively isolate the collector area 19 from the emitter area 17 .
  • the first area 13 b of the top surface 13 a stacks the lower cladding layer 29 , the active area 15 , and the upper cladding area 27 thereon.
  • the emitter area 17 on the second area 13 c where the emitter area may be made of a semiconductor material 23 of the first conduction type, is in physically contact to the side of the lower cladding area 29 , that of the active area 15 , and that of the upper cladding area 27 .
  • the collector area 19 which is provided on the third area 13 d and may be made of semiconductor material 25 with the first conduction type, is in physically contact to the other side of the lower cladding area 29 , that of the active area 15 , and that of the upper cladding layer 27 .
  • the semiconductor laser 11 a further provides a first electrode 31 a on the emitter area 17 and a second electrode 31 b on the collector area 31 b , where the first and second electrodes, 31 a and 31 b , may form non-rectifier contacts to the emitter area 17 and the collector area 19 , respectively.
  • the emitter area 17 and the collector area 19 are laterally arranged on the substrate 13 ; accordingly, the first and second electrodes, 31 a and 31 b , may be arranged apart from the mesa MS where the mesa MS propagates the light having relatively longer wavelength.
  • the substrate 13 of the arrangement B may be made of also insulating or semi-insulating material and has the top surface 13 a .
  • the first area 13 b stacks the lower cladding layer 29 , the active area 15 , and the upper cladding layer 27 thereon.
  • the emitter area 17 on the second area 13 c provides a first semiconductor layer 33 a that is in physically contact to the side of the mesa MS and a second semiconductor layer 33 b on the first semiconductor layer 33 a .
  • the first semiconductor layer 33 a as FIG. 2 indicates, may be made of a semiconductor material having the conduction band in the bottom level thereof substantially equal to or higher than the upper energy level E 3 , which enables the carrier injection from the emitter area 17 into the active area 15 without supplying a large bias.
  • the second semiconductor layer 33 b may be made of semiconductor material having refractive index smaller than equivalent refractive index of the active area 15 .
  • the collector area 19 on the third area 13 d may include a third semiconductor layer 35 a that is in physically contact to the other side of the mesa MS, and a fourth semiconductor layer 35 b on the third semiconductor layer 35 a .
  • the third semiconductor layer 35 a may be made of semiconductor material having the conduction band in the bottom energy level thereof equal to or lower than the lower level E 2 , or preferably lower than the relaxation level E 1 .
  • the semiconductor laser 11 b of the arrangement B enhances the extraction of the carriers into the collector area 19 from the active area 15 .
  • the fourth semiconductor layer 35 b may be made of semiconductor material having refractive index smaller than equivalent refractive index of the active area 15 .
  • the semiconductor laser 11 b further provides the first electrode 31 a and the second electrode 31 b on the emitter area 17 and the collector area 19 , where the electrodes, 31 a and 31 b , each make non-rectifier contacts to the respective areas, 17 and 19 .
  • An arrow C 3 indicates the carrier flowing in the emitter area 17
  • another arrow C 4 indicates the carrier flowing in the connector area 19 .
  • the semiconductor laser 11 c provides an electrically conductive substrate 13 . Because of the conductive characteristic of the substrate 13 , the semiconductor laser 11 c is necessary to isolate the emitter area 17 electrically from the substrate 13 . Accordingly, the semiconductor laser 11 c provides an isolation area 37 on the substrate 13 in the first area 13 b and the second area 13 c , where the isolation area 37 is made of electrically insulating or semi-insulating material and may electrically isolate the active area 15 and the emitter area 17 from the substrate 13 .
  • the isolation area 37 may operate as a lower cladding layer. In such a case, the lower cladding layer 29 may be omitted.
  • the first area 13 b of the substrate 13 stacks the lower cladding layer 29 , the active area 15 , and the upper cladding layer 27 thereon as interposing the isolating isolation area 37 against the substrate 13 .
  • the emitter area 17 on the second area 13 c which has the first conduction type, is in physically contact to the side of the lower cladding layer 27 and that of the active area 15 .
  • the collector area 19 on the third area 13 d which also has the first conduction type, is in physically contact to a side of the isolation area 37 , the other side of the lower cladding layer 29 , and the other side of the active area 15 .
  • the semiconductor laser 11 c of the present embodiment provides the first and second semiconductor layers, 33 a and 33 b , in the emitter area 17 , where the first semiconductor layer 33 a is in contact to the side of the mesa MS. Also, the collector layer 19 provides the third and fourth semiconductor layers, 35 a and 35 b , where the third semiconductor layer 35 a is in contact to the other side of the mesa MS.
  • the emitter area 17 exactly, the second semiconductor layer 33 b in the emitter area 17 , provides the first electrode 31 a thereon, which is similar to those of the arrangement B; but, a third electrode 31 c instead of the second electrode 31 b of the arrangement B is provided in a back surface 13 e of the substrate 13 .
  • the third electrode 31 c makes non-rectifier contact to the back surface 13 e of the substrate 13 .
  • Arrows, C 5 and C 6 , indicated in FIG. 1 show the carrier flowing from the first electrode 31 a to the third electrode 31 c.
  • the quantum well structure 21 provides well layers, for instance, two well layers, 21 a and 21 b , and one or more barrier layers to divide these well layers.
  • the inner barrier layer 21 d is thinner than the outer barrier layer 21 c to tightly couple the wave functions in the respective well layers, 21 a and 21 b , that penetrate into the inner barrier layer 21 d .
  • the coupled quantum well provides an arrangement of the line symmetry with respect to a center of the inner barrier layer 21 d .
  • Such an arrangement may form the relaxation level E 1 lower than the lower energy level E 2 by an amount substantially equal to energy of an LO phonon.
  • the carriers fallen into the lower energy level E 2 from the upper energy level E 3 may immediately fall to the relaxation level E 1 by the phonon scattering.
  • the coupled quantum well may enhance the overlapping of the wave function attributed to the upper energy level E 3 with the wave function of the lower energy level E 2 , which may increase the probability of the radiative transition between the levels, E 3 and E 2 , and resultantly the efficiency of the laser emission. Table below summarizes parameters of the coupled quantum well of the embodiment.
  • the semiconductor laser of the type of the present invention is unnecessary to accompany the active area with an injection layer that is inevitable in a semiconductor layer having a type of the cascade quantum well structure, which may expand a range of variation of the quantum well structure.
  • the coupled quantum well of the embodiment may induce tensile stress in the barrier layers, 21 c and 21 d , while, compressive stress in the well layers, 21 a and 21 b , by adjusting lattice constants of respective layers, 21 a to 21 d , these two stresses may be totally and substantially compensated in the whole coupled quantum well. This enables to obtain a large difference between the energy levels without degrading crystal quality. A larger difference ion the energy levels results in the suppression of the leaking of carriers, which means to improve temperature characteristics of the semiconductor laser and the range of the oscillation wavelength.
  • a substrate made of indium phosphide (InP) is prepared.
  • the process next grows on the InP substrate another InP layer doped with iron (Fe) for the lower cladding layer 29 .
  • the process grows the active area 15 including the unit cells 15 a having four semiconductor layers, 21 a to 21 d , described above.
  • another Fe-doped InP layer for the upper cladding layer 27 is grown on the active area 15 .
  • the semiconductor stack may be provided on the substrate 13 .
  • a first mask preferably made of silicon nitride (SiN) on a top surface of the semiconductor stack, a portion of the semiconductor stack is etched using the first mask as an etching mask, where the first mask covers a portion of the mesa MS and the collector area 19 so as to expose the semiconductor stack for the emitter area 17 .
  • the Si-AiInAs layer preferably has a thickness through which electrons are hard to be tunneled, that is, the Si—AlInAs layer is preferably thicker than 10 nm.
  • the process forms a second mask that covers the emitter area 17 and the semiconductor stack for the mesa MS.
  • a portion of the semiconductor stack exposed from the second mask is etched and the mesa MS may be formed.
  • the Si—GaInAs preferably has a relatively thinner thickness of 10 to 50 nm, which strengthens the optical confinement laterally and stabilizes the transverse mode of the laser emission.
  • the process After the formation of the emitter area 17 , the active area 15 , and the collector area 19 , the process forms the n-type electrodes, 31 a and 31 b , on the emitter area 17 and the collector area 19 , respectively, by for instance, the metal evaporation and subsequent lift-off technique. Then, grinding the back surface of the substrate 13 , and cleaving thus thinned substrate 13 , laser bars each including the semiconductor lasers are formed.
  • the process may interpose a semiconductor material between the first and second semiconductor layers in the emitter area 17 , where the semiconductor material has intermediate bandgap energy between the Si-doped InP and the Si-doped AiInAs to form a stack of InP/AlGaInAs/AlInAs, where AlGaInAs has bandgap energy between those of InP and AlInAs.
  • the collector area 19 may have a stacking of InP/GaInAsP/GaInAs, where GaInAsP has bandgap energy between those of InP and GaInAs.
  • Those intermediate semiconductor materials, AlGaInAs in the emitter area 17 and GaInAsP in the collector area 19 may moderate respective hetero interfaces and enable the semiconductor laser operable in relatively lower biases.
  • the process may first grow a semi-insulating InP layer on the conductive substrate 13 . Then, a portion of the semi-insulating layer corresponding to the collector area 19 is removed to expose the conductive substrate 13 . Thereafter, similar to the aforementioned processes, forming the semiconductor stack for the lower cladding layer 29 , the active area 15 , and the upper cladding layer 27 ; etching a portion of the semiconductor stack, re-growing the semiconductor layers; the semiconductor laser having the arrangement C may be completed.
  • the quantum well structure of the second embodiment of the present invention may dope impurities showing the conduction type same with that of the carriers within at least a portion of the barrier layers.
  • the barrier layer partially doped may enhance the injection efficiency of the carriers into the well layers.
  • the intermediate layer 21 cb may have doping density of preferably less than 10 17 cm ⁇ 3 to suppress optical losses due to the free carrier absorption.
  • the intermediate layer 21 cb may enhance the lateral conductivity within the layer, where the carriers injected from the emitter area 17 may reach regions in the well layers apart from the emitter area 17 .
  • FIG. 5 shows still another arrangement of the semiconductor laser of the present invention, which are modified from the arrangements shown in FIG. 1 .
  • the semiconductor laser 12 shown in FIG. 5 has features distinguishable from the semiconductor laser 11 shown in FIG. 1 that the semiconductor laser 12 has an electrode area 20 as the collector area 19 of the aforementioned semiconductor laser 11 .
  • Other arrangements in the semiconductor laser 12 are substantially same with those of the aforementioned semiconductor laser 11 .
  • the electrode area 20 which is formed on the third area 13 d of the top surface 13 a of the substrate 13 , provides a metal 36 extending along the direction Z and in contact to the active area 15 .
  • the emitter area 17 and the electrode area 20 area divided by the mesa MS, and the carries injected into the emitter area 17 flow into the electrode area 20 through the active area 15 .
  • the carriers injected into the emitter area 17 are supplied to the active area 15 in the higher energy level as the carriers CAE, cause the radiative emission from the higher energy level to the lower energy level in the active area 15 , and finally stream into the metal 36 in the electrode area 20 .
  • the semiconductor laser 12 may show the function of the radiative transition by the unipolar carriers without providing the cascaded radiative transition also by the unipolar carriers.
  • the active area 15 which may be formed within he mesa MS, may include the upper cladding layer 27 as the first cladding layer and the lower cladding layer 29 as the second cladding layer, where the active area 15 is sandwiched between the upper and lower cladding layers, 27 and 29 .
  • the upper cladding layer 27 may have the resistivity greater than that of the active area 15 in an average thereof
  • the lower cladding layer 29 may also have the resistivity greater than that of the active area in an average thereof. Because the upper and lower cladding layers, 27 and 29 , have a function to confine carries electrically within the active area in addition to the function to confine light within the active layer, the carrier injection from the emitter area 17 into the active area 15 may be effective.
  • the upper and lower cladding layers, 27 and 29 may be preferably made of insulating and/or semi-insulating material, or semiconductor material having the conduction type thereof opposite to the carriers; specifically, when the carriers are electrons, the upper and lower cladding layers, 27 and 29 , may be made of p-type semiconductor material.
  • the electrode area 20 in particular, the metal 26 thereof is in contact to the side 15 c of the active area 15 and form the non-rectified contact against the active area 15 .
  • the upper and lower cladding layers, 27 and 29 have refractive indices thereof smaller than refractive index of the active area 15 in an average.
  • the emitter area 17 has refractive indices smaller than the average refractive index in the active area 15 .
  • this arrangement of the refractive index in the emitter area 17 and the active area 15 may laterally confine light generated in the active area 15 ; while, the arrangement of the upper and lower cladding layers, and the active area 15 may vertically confine the light within the active area 15 .
  • the arrangement A 1 for the semiconductor laser 12 a which traces the semiconductor laser 12 , provides the metal 36 including a first portion 36 a and a second portion 36 b , where the second portion 36 b is in contact to the side 15 c of the mesa MS, namely, the side of the upper and lower cladding layers, 27 and 29 , and that of the active area 15 .
  • the first portion 36 a is directly in contact to the top surface 15 a of the substrate 15 .
  • the semiconductor laser 12 a further provides the first electrode 31 a in the top of the emitter area 17 , while the first portion 36 a of the metal 36 gives the function of the second electrode 32 b .
  • the carriers C 1 injected from the first electrode 31 a into the emitter area 17 come within the active area 15 and the active area 15 exhausts the carriers C 2 into the second portion 36 b of the metal.
  • the arrangement B 1 which corresponds to the arrangement B in FIG. 1 , has a feature that the emitter area 17 provides two portions, 33 a and 33 b , where the former portion 33 a is directly in contact to the top surface 13 a of the substrate 13 and the side 15 b of the mesa MS, namely, the sides of the upper and lower cladding layers, 27 and 29 , and the side of the active area 15 ; while, the latter portion 33 b is provided on the first portion 33 a .
  • the first portion 33 a gives the energy level E 17 of the bottom of the conduction band that is substantially equal to or higher than the upper energy level E 3 in the well layers, 21 a and 21 b .
  • the second portion 33 b has the refractive index smaller than the equivalent refractive index of the active area 15 .
  • the arrangement of the double semiconductor layers, 33 a and 33 b may enhance the carrier injection into the well layers, 21 a and 21 b , in the active area 15 without degrading the optical confinement within the active area 15 , where the arrows, C 3 and C 4 , indicate the carrier flowing from the first electrode 31 a to the second electrode 32 b as those in the arrangement B of the aforementioned embodiment.
  • the arrangement C 1 in FIG. 5 which corresponds to the arrangement C in FIG. 1 , has a feature that the substrate 13 is electrically conductive and the second electrode 32 c is provided in the back surface 13 e of the substrate 13 . Because of the electrical isolation of the emitter area 17 and the mesa MS from the second electrode 32 c , the semiconductor laser 12 c provides the isolation area between the emitter area 17 and the substrate 13 , and between the mesa MS and the substrate 13 , that is, the isolation area 37 is provided beneath the emitter area 17 and the mesa MS. Removing the lower cladding layer 29 , the isolation area 37 in a portion beneath the mesa MS may show the function of the lower cladding layer.
  • the emitter area 17 similar to the arrangement B 1 , provides the double layers, 33 a and 33 b , made of semiconductor materials whose functions are same with those in the arrangement B 1 .
  • the semiconductor laser 12 d also provides the electrically conductive substrate 13 and the isolation area 37 to isolate the emitter area 17 and the mesa MS electrically from the substrate 13 .
  • the isolation area 37 may show the function of the lower cladding layer 29 against the active area 15 . In such a case, the lower cladding layer 29 may be removed.
  • the semiconductor laser 12 d provides an upper cladding layer 28 that includes a first portion 28 a and a second portion 28 b , where the former portion 28 a is in contact to the emitter area 17 , while, the latter portion 28 b is in contact to the electrode area 20 .
  • a feature of the upper cladding layer 28 of the embodiment is that the first portion 28 a has a thickness H 1 greater than a thickness H 2 of the second portion 28 b .
  • the former thickness H 1 may be, for instance, 1 to 5 ⁇ m, while the latter thickness H 2 is, for instance, 0.2 to 2.0 ⁇ m.
  • the first and second portions, 28 a and 28 b may have widths, W 1 and W 2 , from 1 to 5 ⁇ m, where the former width W 1 of the first portion 28 a is wider than the latter width W 2 of the second portion 28 b . Accordingly, the light propagating along the mesa MS may show a profile P whose peak is offset toward the emitter area 17 .
  • the process first grows semiconductor layers, 41 to 43 , for the lower cladding layer 29 , the active area 15 , and the upper cladding layer 27 sequentially on the substrate 13 by, for instance, the MOCVD or MBE technique.
  • the layer 41 which is grown for the lower cladding layer 29 , may made of InP doped with irons (Fe).
  • the layer 42 includes unit cells each having four layers of the quantum well structure.
  • the layer 43 may be also made of InP doped with irons.
  • the semiconductor stack 40 for the mesa MS is formed.
  • the process prepares a first mask M 1 , which may be made of silicon nitride (SiN), on the semiconductor stack 40 for forming the first stripe S 1 , FIG. 7( b ) .
  • the first mask M 1 provides an opening M 1 A above the second area 13 c .
  • a portion of the semiconductor stack 40 exposed in the opening M 1 A is fully etched so as to expose the top surface 13 a of the substrate 13 , which forms the first stripe S 1 as shown in FIG. 7( c ) .
  • the process carries out the selective growth in the second area 13 c without removing the first mask M 1 left on the first stripe S 1 , as shown in FIG. 7( d ) .
  • the selective growth sequentially grows the first semiconductor layer 33 a , which may be made of silicon (Si) doped AlInAs, and the second semiconductor layer 33 b , which may be made of also Si doped InP.
  • the first semiconductor layer 33 a preferably has a thickness for electrons not to tunnel therethrough, specifically, thicker than 10 nm. After the selective growth of the semiconductor layers, 33 a and 33 b , the process removes the first mask M 1 .
  • the second stripe S 2 is formed.
  • the process prepares the second mask M 2 , which may be made of also silicon nitride (SiN), on the emitter area 17 and the semiconductor stack 40 .
  • the second mask M 2 provides an opening M 2 A in a portion corresponding to the electrode area 20 , within which the top surface of the semiconductor stack 40 is exposed.
  • the process removes a part of the semiconductor stack 40 corresponding to the electrode area 20 until the top surface 13 a of the substrate 13 appears.
  • the second mask M 2 is removed as shown in FIG. 8( b ) .
  • the process prepares a third mask M 3 , which is shown in FIG. 8( c ) , where the third mask M 3 , which may be made of resin, typically a photoresist, provides an opening M 3 A on the emitter area 17 and another opening M 3 B in the electrode area 20 .
  • the first electrode 31 a is deposited within the opening M 3 A, which is on the second semiconductor layer 33 b in the emitter area 17
  • the metal 36 is deposited within the other opening M 3 B on the substrate 13 each by sequential processes of the metal evaporation and the subsequent lift-off technique that removes portions of the evaporated metal left on the third mask M 3 concurrently with the removal of the third mask M 3 .
  • an intermediate device SP 1 for the semiconductor laser 12 may be obtained, as shown in FIG. 8( d ) .
  • the process for the semiconductor laser 12 thus described may further grow, in the step shown in FIG. 7( c ) , an intermediate semiconductor layer between the first and second semiconductor lasers, 31 a and 31 b .
  • the intermediate semiconductor layer has bandgap energy between those of AiInAs of the first semiconductor layer 33 a and InP of the second semiconductor layer 33 b , where the intermediate semiconductor layer may be made of AlGaInAs as a typical example.
  • Such an arrangement of the semiconductor layers in the emitter area 17 may effective reduce the band offset between the first and second semiconductor layers, 33 a and 33 b , and the semiconductor laser 12 may be operable in further reduced biases.
  • FIGS. 9A to 9D Next, another process of forming the semiconductor laser 12 d shown in FIG. 6 will be described as referring to FIGS. 9A to 9D .
  • the process prepares a mask MK, which may be made of also silicon nitride (SiN), on the emitter area 17 and the semiconductor stack 40 .
  • the mask MK provides an opening MA that exposes a portion of the top surface of the semiconductor layer 43 in the first area 13 b and the top surface of the semiconductor layer 43 in the third area 13 d .
  • the third semiconductor layer 43 is half etched, as shown in FIG. 8( a ) . That is, the etching does not expose the second semiconductor layer 43 .
  • the process fully removes the mask MK.
  • the second mask M 2 P which may be made of silicon nitride (SiN), covers the first area 13 b and the second area 13 c . That is, the second mask M 2 P exposes the top surface of the third semiconductor layer 43 in the third area 13 d , where the exposed third semiconductor layer 43 is half etched in the preceding step.
  • the third to first semiconductor layers, 43 to 31 , on the third area 13 d are sequentially etched using the second mask M 2 P so as to exposes the substrate 13 , which forms the second stripe S 2 P as shown in FIG. 9( b ) .
  • the process fully removes the second mask M 2 P.
  • the process further prepares still another mask M 3 P, which may be made of resin, typically a photoresist, that provides an opening M 3 C in the second area 13 c for forming the electrode 31 a and another opening M 3 D in the third area 13 d for forming the metal 36 .
  • Deposition of the metal within the openings, M 3 C and M 3 D, by the metal evaporation and the subsequent lift-off process form the electrode 31 d and the metal 36 in respective areas, 13 c and 13 d .
  • the intermediate device SP 2 for the semiconductor laser 12 d may be formed. Grinding the back surface of the substrate and cleaving the substrate, laser bars each including the semiconductor lasers are completed.
  • the process for forming the semiconductor stack 40 grows an semi-insulating InP directly on the substrate 13 in advance to grow the first semiconductor layer 41 . Then, portions of the semi-insulating InP layer in the third area 13 d are removed by the sequential processes of the photolithography and the selective etching of the semi-insulating InP layer in the third area. Then, the process may form the semiconductor stack for the mesas, S 1 and S 2 , perform the processes subsequent to that shown in FIG. 7( b ) .
  • the process may leave the semi-insulating InP layer and grow the semiconductor layers, 41 to 43 , for the semiconductor stack 40 on the left semi-insulating InP layer; but, the process shown in FIG. 8( c ) or 9 C etches not only the semiconductor layers, 41 to 43 , in the third area 13 d but the semi-insulating InP layer left beneath the first semiconductor layer 41 so as to expose the surface of the conductive substrate 13 .
  • the semiconductor laser 12 c having the conductive substrate 13 , or the back electrode 32 c may be obtained.
  • the semiconductor laser according to the present invention has a feature distinguishable from those of quantum cascade lasers in that the injected carriers are laterally transported within the well layers, which means that no potential barriers exist along the transportation of the carriers. Accordingly, the semiconductor layer of the invention may be operable by relatively lower biases. Also, the semiconductor laser of the invention may enhance the optical gain by providing a plurality of the quantum well structure 21 without increasing the operational bias. Even the semiconductor layer provides a lot of unit cells each having the quantum well structure 21 to enhance the optical gain thereof, the operational bias is unnecessary to be increased. Thus, the semiconductor laser of the invention may save power consumption compared with conventional cascade lasers that show lesser efficiency due to the tunneling of the carriers through the barrier layers.

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11196233B2 (en) * 2019-01-30 2021-12-07 Sumitomo Electric Industries, Ltd. Quantum cascade laser

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4408330A (en) * 1979-12-07 1983-10-04 Kabushiki Kaisha Towa Giken Field effect semiconductor laser, method of modulation thereof
US5073892A (en) * 1989-06-12 1991-12-17 Hitachi, Ltd. Semiconductor laser device
US5111255A (en) * 1990-06-05 1992-05-05 At&T Bell Laboratories Buried channel heterojunction field effect transistor
US5164797A (en) * 1988-06-17 1992-11-17 Xerox Corporation Lateral heterojunction bipolar transistor (LHBT) and suitability thereof as a hetero transverse junction (HTJ) laser
US6002142A (en) * 1996-09-30 1999-12-14 Xerox Corporation Integrated optoelectronic structures incorporating P-type and N-type layer disordered regions
US20110103420A1 (en) * 2009-10-29 2011-05-05 Sony Corporation Laser diode
US20130177036A1 (en) * 2008-07-28 2013-07-11 Avago Technologies General Ip (Singapore) Pte. Ltd. Three-terminal vertical cavity surface emitting laser (vcsel) and a method for operating a three-terminal vcsel
US20130182736A1 (en) * 2012-01-17 2013-07-18 Sumitomo Electric Industries, Ltd. Quantum cascade laser
US20140050241A1 (en) * 2012-08-20 2014-02-20 The Board Of Trustees Of The University Of Illinois Semiconductor Device And Method For Producing Light And Laser Emission
US20140273323A1 (en) * 2013-03-15 2014-09-18 Mattew H. Kim Method of manufacture of advanced heterojunction transistor and transistor laser
US20150171197A1 (en) * 2012-08-17 2015-06-18 Opel Solar, Inc. Single Electron Transistor Device

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5739543A (en) * 1993-11-24 1998-04-14 The Furukawa Electric Co., Ltd. Optical semiconductive device with inplanar compressive strain
US7271418B2 (en) * 2004-09-24 2007-09-18 National Central University Semiconductor apparatus for white light generation and amplification
US20060215718A1 (en) * 2005-03-28 2006-09-28 Nat. Inst. Of Inf. & Comm. Tech., Inc. Admin. Agcy Quantum cascade laser
JP5355599B2 (ja) * 2011-01-19 2013-11-27 株式会社東芝 半導体発光装置およびその製造方法
JP2013165152A (ja) * 2012-02-10 2013-08-22 Nippon Telegr & Teleph Corp <Ntt> プラズモン薄膜レーザ

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4408330A (en) * 1979-12-07 1983-10-04 Kabushiki Kaisha Towa Giken Field effect semiconductor laser, method of modulation thereof
US5164797A (en) * 1988-06-17 1992-11-17 Xerox Corporation Lateral heterojunction bipolar transistor (LHBT) and suitability thereof as a hetero transverse junction (HTJ) laser
US5073892A (en) * 1989-06-12 1991-12-17 Hitachi, Ltd. Semiconductor laser device
US5111255A (en) * 1990-06-05 1992-05-05 At&T Bell Laboratories Buried channel heterojunction field effect transistor
US6002142A (en) * 1996-09-30 1999-12-14 Xerox Corporation Integrated optoelectronic structures incorporating P-type and N-type layer disordered regions
US20130177036A1 (en) * 2008-07-28 2013-07-11 Avago Technologies General Ip (Singapore) Pte. Ltd. Three-terminal vertical cavity surface emitting laser (vcsel) and a method for operating a three-terminal vcsel
US20110103420A1 (en) * 2009-10-29 2011-05-05 Sony Corporation Laser diode
US20130182736A1 (en) * 2012-01-17 2013-07-18 Sumitomo Electric Industries, Ltd. Quantum cascade laser
US20150171197A1 (en) * 2012-08-17 2015-06-18 Opel Solar, Inc. Single Electron Transistor Device
US20140050241A1 (en) * 2012-08-20 2014-02-20 The Board Of Trustees Of The University Of Illinois Semiconductor Device And Method For Producing Light And Laser Emission
US20140273323A1 (en) * 2013-03-15 2014-09-18 Mattew H. Kim Method of manufacture of advanced heterojunction transistor and transistor laser

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11196233B2 (en) * 2019-01-30 2021-12-07 Sumitomo Electric Industries, Ltd. Quantum cascade laser

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Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION